This invention relates generally to portable devices which can be used on a broad range of seating furniture to assist an elderly, infirm, handicapped or overweight person in gently sitting down and rising from the seated position.
Dedicated furniture to accomplish this is well known and this field consists in the main of chairs having moving seats which are powered electrically or by fluid power. Another type of such furniture uses passive energy storage elements such as springs to support the person during seating and to urge the person upwards when rising.
Portable devices that can be used on conventional seating furniture are also known to exist and these too are either powered or passive. These portable devices have the advantage over dedicated furniture of lower cost and versatility in that the user may quickly transfer the device from chair to chair and even take it travelling.
The passive, spring-based systems are simpler and less expensive than the powered ones. They also are free of the need for electrical connections and have the advantage of ease of control if properly designed, since an electrically powered seat lift must for safety move at a fixed slow rate of speed. The passive arrangements do, however, ideally require some form of adjustment to match the spring forces to the weight of the occupant. Spring assisted chairs of dedicated construction are generally shown in the following U.S. Pat. Nos. 4,538,853 and 4,573,736 to Levenberg; U.S. Pat. No. 4,690,457 to Poncy et al. U.S. Pat. No. 4,852,849 to Jones and U.S. Pat. No. 4,979,726 to Geraci.
Spring-assisted portable seat assist devices have been generally shown in the following U.S. Pat. No. 5,082,327 to Crisp; U.S. Pat. No. 4,688,851 to Whiteford; U.S. Pat. No. 3,659,897 to Wright.
These arrangements contain certain deficiencies whose resolutions are objects of this invention. Known spring-assisted arrangements, both in dedicated furniture and portable form, generally have a latch mechanism for releasably securing the seating member to allow the springs to assist the occupant in rising. These known latching arrangements require the user to activate the latch manually before rising. Since the typical user of such a device is physically impaired, it is desirable that they have both hands free to steady themselves on the arms of the chair or on a walker or a cane or other suitable handle as they rise. Latching devices can impair this freedom. In addition, latching systems have disadvantages relating to safety and convenience: in order to collapse the device for transportation or storage, (or in the case of dedicated furniture, for use as a normal chair) large amounts of energy must be stored in it before latching the seat in the down position. This presents the hazard of accidental unlatching. Furthermore, in the case of adjustable arrangements, a lighter person may sit on the latched device than the person for whom the spring forces were set, giving rise to the hazard of an overly energetic lift.
The known spring-assisted arrangements typically use a moving seat element which is an upholstered flat and rigid panel mounted pivotally to the front edge of a base element or the chair structure. When the seat is in the fully lifted position it is therefore at a considerable angle to the horizontal, thus a substantial component of the lift force is forward rather than upward and the chair may slide away from the occupant if not blocked from moving on the floor. In addition, the slope of the seat may cause the impaired person to slide down it.
Accordingly, it is seen that a there still exists a need for a portable passive seating assist apparatus which has a stable seating surface and which is safely and easily used by the physically infirm.
It is an object of this invention to safely assist an infirm person in sitting down and rising from a conventional chair, couch, bench, wheel chair or the like.
It is also an object of this invention to provide a device which is inexpensive, simple, lightweight and provides a comfortable and stable seating surface at all stages of the lifting action.
It is a further object of this invention to provide a lifting device which is so configured as to not require a latch in the closed position.
It is a further object of this invention to provide an adjustable spring assembly which can be quickly changed to suit persons of various weights and infirmities and which can be deactivated to enable easily collapsing the device for storage and transportation.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention.